9/18/2019
Introduction
Why have a survey design?
This type of survey can be useful for the discovery of zebra mussels
Transect sampling is one approach to cover area quickly
A formal design controls effort and area surveyed so we can estimate density.
Methods
Three survey designs to explore sampling tradeoffs
Estimating detection with two observers
- First observer marks each detected cluster
- Second observer looks for new clusters
- New detections inform our estimate of detection probability
Using the additional information from distance surveys
We compared designs across densities
Main Findings
Detection probability estimates
- Detection estimates were consistent between lakes
- In transect surveys the detection probability by either observer detecting the zebra mussel was > 90%.
- In distance surveys detection probability by either observer was around 50%
Density estimates
- Estimates from transect surveys were consistently low
- Variance of Quadrat estimates was highest at low to medium density
Recommendations
- Apply distance surveys with two divers at low to moderate densities
- Quadrat surveys at high densities
Acknowledgements
Jake Ferguson
Michael McCartney
Naomi Blinick
Leslie Schroeder
Sarah Baker
Aislyn Keyes
Austin Hilding
Kylie Cattoor
Keegan Lund
